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Functional appliance therapy accelerates and enhances condylar growth
A B M Rabie1, T T She, Urban Hägg
1Department of Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China. rabie@hkusua.hku.hk
Summary
Forward mandibular positioning accelerates chondrocyte differentiation and cartilage matrix formation. Functional appliance therapy enhances condylar growth without causing subnormal growth later.
Area of Science:
- Biomedical Engineering
- Developmental Biology
- Orthodontics
Background:
- Chondrocyte differentiation is crucial for skeletal development.
- Sox 9 and type II collagen are key regulators and components in cartilage formation.
- Understanding condylar growth mechanisms is vital for orthodontic interventions.
Purpose of the Study:
- To quantitatively assess Sox 9 and type II collagen expression during forward mandibular positioning.
- To compare this expression pattern with natural mandibular growth.
- To evaluate new bone formation associated with functional appliance therapy.
Main Methods:
- Using 5-week-old female Sprague-Dawley rats.
- Quantitative assessment of Sox 9 and type II collagen expression.
- Monitoring new bone formation during and after appliance use.
Main Results:
- Forward mandibular positioning accelerated and enhanced Sox 9 and type II collagen expression.
- Substantial new bone formation was observed during mandibular advancement.
- No significant difference in bone formation was found post-appliance removal compared to natural growth.
Conclusions:
- Functional appliance therapy accelerates chondrocyte differentiation and cartilage matrix formation.
- This leads to enhanced condylar growth.
- The enhanced growth is sustained and does not result in subsequent subnormal growth.